N-methylol-p-vinyl benzamide



'Ser. No. 177,136 filed August 1, 1950.

Patented Aug. 25, 1953 N-METHYLOL-p-VINYL BENZAMIDE John Noel Milne,Epsom Downs, Donald Faulkner, Epsom, and Charles Edward Hollis, Ewell,Eng- 1 land, assignors to The Distillers Company Limited, Edinburgh,Scotland, a British company No Drawing. Original a Serial No. 177,136.

pplicatlon August 1, 1950, Divided and, this application September 13,1951,Serial No. 247,567. In Great Britain August 25, 1949 1 Claim. (Cl.260 558) This invention relates to a new polymerisable compound,para-vinylbenzamide, to its polymers and copolymers and to resinsproduced by treating it with formaldehyde before, during or afterpolymerisation or copolymerisation.

P-vinylbenzamide, as a derivative of styrene, will polymerise byaddition polymerisation while by virtue of its amido-group it will enterinto condensation reactions with formaldehyde its polymers, compoundsyielding formaldehyde under the reaction conditions and compoundscontaining reactive hydroxy-methyl and similar groups. a

This application is a division of application Matter described but notclaimed herein is claimed in said patent.

The new monomer may be prepared from paracyanostyrene by hydrolysis asdescribed in Example 1.

Example 1 A mixture of 6.5 gm. (0.05 mol.) of p-cyanostyrene. 46 ml.(0.4 mol.) of 30% hydrogen peroxide and 54 ml. of water was stirredvigorously, while a solution of 2 gm. (0.05 mol.) of sodium hydroxide inm1. of water was added rapidly. A vigorous reaction set in and thetemperature rose spontaneously until the mixture was almost at theboiling point. When the reaction slackened, a further 46 ml. (0.4 mol.)of undiluted hydrogen peroxide was added and the mixture was heated onthe water bath for 5 hours. After standing, the solid product wasfiltered 01f and washed with water and, by repeated recrystallisationfrom water, pure p-vinylbenzamide was* obtained in the form ofcolourless needles, M. Pt. 169170 C. Elementary analysis showed thepresence of carbon, hydrogen and nitrogen in the following percentagesby weight: C, 73.48; H, 6.45; N, 9.5. (Required for CQHBNO) C, 73.43; H,6.17; N, 9.52. i

The preparation of p-vinylbenzamide from pcyanostyrene may also becarried out via p-vinylbenzoic acid and p-vinylbenzoyl chloride, asfollows:

Example 2 8.8 gm. (0.06 mol.) of thoroughly dried powderedp-vinylbenzoie acid preparedby the method of Marvel and Overberger, J.A. C. S. 1945, 67, 2251, was treated with 14.2 gm. (0.12 mol.) offreshly redistilled thionyl chloride and the mixture was allowed tostand'at room temperature in a flask from which moisture was excluded bymeans of a. calcium chloride tubes Sulphur dioxide and hydrogen chloridewere slowly evolved until, after about hours, the originally pasty masswas converted to a mobile, pale brown liquid and the reaction wascomplete. Excess thionyl chloride was distilled oil under reducedpressure by means of a water bath maintained at 25-35 0., leaving thecrude acid chloride as a pale brown, mobile liquid which was used forthe next stage without any purification.

The acid chloride was dissolved in ml. of dry benzene, the solutionfiltered to remove traces of insoluble matter and dry ammonia bubbled inuntil no further precipitation of solid took place. More benzene wasadded from time to time, as the suspension of precipitated amide becameso pasty as to prevent passage of ammonia gas. 1

The suspended solid was separated by filtration, washed with benzene andsucked dry. The product was shaken with 100 ml. of 5% sodium carbonatesolution to remove any unchanged pvinylbenzoic acid or acid chloride,filtered, washed with water and dried. The dry product was dissolved inml. of alcohol, treated with charcoal, filtered hot and poured into 700ml. of boiling water. The aqueous alcoholic solution was boiled for afew minutes, again filtered hot and allowed to cool slowly. Finally, theamide which separated on cooling was filtered off, washed with water anddried in vacuo. The yield was 6.6 gm. (79% based on p-vinylbenzoic acid)of fine white needles which had M. P. 168 (not depressed on mixing witha sample of p-vinylbenzamide prepared by hydrolysis of p-cyanostyrenewith alkaline hydrogen peroxide as described in Example 1).

P-vinylbenzamide, by virtue of its possession of a reactive vinyl group,may be additionpolymerised by various means, for example by heating, bythe action of peroxides and other known polymerisation catalysts, or bythe action 101' radiation of suitable wavelengths. The monomer may bepolymerised alone in the pure state, or in solution in suitablesolvents, or when emulsified or dispersed in a suitable medium, forexample water. P-vinylbenzamide may also be copolymerised with variousother monomers such as styrene, and materials copolymerisable withstyrene. Pure poly-p-vinylbenzamide may be obtained as a hard,transparent resin, relatively insoluble in most solvents, probably owingto the highly polar nature of the amido-groups present along the polymerchain, the solubility behaviour depending to some extent on themolecular weight, 1. e. on the conditions under which it is produced.For instance, when polymerised alone, the polymer is unattacked byboiling dimethyl formamide and slightly swollen by boiling cresol. Whenprepared by heating in a solution of toluene, polymers may be obtainedwhich are believed to be of lower molecular weight and which dissolvecompletely in cresol'. It is also possible that chemical cross-linkingof the polymer may be induced under severe conditions by elimination ofammonia between amide-groups on adjacent chain molecules.

The following examples illustrate the production of the new polymers andcopolymers:

Example 3,-

A sample of p-vinylbenzamide was sealed in a glass tube and heated to180 C'. for 2 hours.v The powdered material melted to a homogeneousliquid and at the end of the polymerisation a hard, transparent, glassyresin was obtained, not melting at 200 C.

Example 4 A 1% solution of p,-vinylbenzami de in, toluene containing.l%by weight on the monomer of benzoyl peroxide Was heated at l; C. for 45hours. The white precipitate of polymer which had formed wasfiltered.off, washed with alcohol to remove traces, oi unpolymerised monomer anddried. The product Was soluble in hot cresol and could be pressed to aclear pale yellow glassy mass at a temperature of 259? C. and a pressureof 1 ton per s uare inch. The polymer obtained in t is example was ofower o e ul Weight than. thatobta ned n Ex mp e th latter teria o lybein ee a in sed b bo lin cres0 Copolymerisation of p-vinylbenzamidewith he m omers ma b a ri d out, by ac h pur m erials alone. o u o n a sab e so to mulsified s e dn as ta le medium. or xam le. when Si e p-v nbeozam e s a sol oi h's 'n point a dts solubility in var ous monomers atreaction tempe ur s. no al s such t at omo e eo s s a n mix e o he. esom osit y we h be btained. it s te a e us o arr o t uoly or sa onin ut olo k i n u d Wm .12 co itio s obo y r of Widel y nao m siti o c n. b taid. rrespective of the solubility of pevinylbenzamide in the othermonomer, The amide-group of pvinylbenzamide is sufficiently resistant tohydrolysis ob rm t. of mulsion o m r on ooerations. Copolymers preparedfrom 95% by Wei ht styrene and: 5%. by-Wei ht p-vinylbenzamide preparedin. emulsion were found to, contain 0.47 of nitrogencompared with thevtheoretical amount of 0.43%, indicating that all; the initialCONI-Iz-groups were still present.

Example 5 A mixture of parts by weight of p-vinylbenzamide, 90 parts ofstyrene and 1, part of 150-.- propylbenzene hydroperoxide was sealed ina glass tube and heated for 5 minutes, at 150 0., whena clear solutionwas formed. The tube was further heated at 100? C. for 13 hours when. acleanglassy copolyjme'r was obtained which was soluble in benzene andinsoluble in alcohol,

Example 6..

A mixture of gm. styrene, 0.3 gm. p-vinylbenzamide and 0.02- gm. benzoylperoxide was sealed in a glass tube which was heatedforl'l hours at 50?C; andthenfor. z hoursat 80 G.- A perfectly, clear, transparent,homogeneous solid Styrene P-vinylbenzamide was obtained which wascompletely soluble in benzene to form a clear, viscous solution. Apurified sample of the polymer was obtained by slowly running thebenzene solution into an excess of methanol with vigorous stirring, theprecipitate being washed with methanol and thoroughly dried. The secondorder transition point (Tm) of the copolymer, as determined by thethermal expansion method, was 975 0.; this may be regarded as a standardmeasure of softening point. 7

Example 7 An amulsion was made of the followin I Parts by weight 9Aqueous sQdillm stearate solution, 2% w./v 20 Aqueous ammonium persulphate, 2% w./v l

by vigorous shaking, and was sealed under air in a glass. tube.Polymerisation: was carried out. by heating theemulsion for 21 hoursat50. C.,agi tating by continuously" rotatin the: tube end;- over-end. Auniform dispersion or latex of cop lymer w bt ned. from. w ich; resi uam nom r was removed y team pp T polymer was precipitated by pouring thestripped latexinto. 5- arts. ot. at n heat n to; boiling an din a litt eir' t ydrochl ri ac d: T e copolymer was dried at49 vacuo and; wasfou5nd to, have a second order transition point of 98. C.

Apart from the intrinsic value of the novel polymer; and1copolymers ofthisinvention asjhigh melting resins suitableforza variety ofapplieations in the plastics; art, they have the valuable property ofbeing rendered insoluble in common solvents, by the action offormaldehyde, its -polymers, or substances yielding formaldehyde withsubsequent or simultaneous heating treatment, the process beingconveniently carried out" by mixing the powdered resin withparaformaldehyde prior to hot pressing, or by treatmentwith aqueousformaldehyde following by drying and baking. It is reasonably certainthat the con version of initially soluble polymers and copolymersderived from p-vinylbenzam-ide into insoluble products is due toacross-linking reaction taking place when formaldehyde reacts withtheamide-group present inthe polymer, leading; to the formation ofmethylol-amido-groups which may eliminate'wateron heating,to-formmethylone or other bridges between'amido-g'roups on adjacentchains, although this theory asto the natureof the reaction:- does notform part of the invention. Foils, films orflbres; made from polymers orcopolymers of p-vinylbenzamide may be treated by soaking in aqueousformaldehyde, fol lowing by a baking process.

The following example illustrates the crosslinking of acopolymer bymeans of aqueous formaldehyde:

Emmple.

A film; Wascast from asoluti'on. in benzene of the copolymer describedin Example 5 by spread;- ing on a glass plate andiallowing the solventto evaporate. Samplesof the film were immersed for 'ho sat n 40%formaldehyde solution slightly acidified with hydrochloric acid and- (bl40% formaldehyde solution made s1ight1y alkaline with caustic soda.

The treated films were then removed, washed with. water, driediand bakedfor- 1: hour'a-t C.- They. werethenfound'to be insoluble inibene zene:but; retainedtheir originalelarity.

By way of "comparison, a film 01' the copolymer which had not beensubjected to formaldehyde treatment remained soluble in benzene afterbaking.

Example 9 Example 10 carried out simultaneously with polymerisation,

although in this procedure the presence of formaldehyde may tend toinhibit polymerisation in some cases. The following example illustratesthis process:

Example 11 An emulsion was made of the following:

Parts by weight Styrene Aqueous sodium stearate solution, 2%

w./V. 20 Aqueous ammonium persulphate, 2

w./v. 1 P-vinylbenzamide 0.09 Formaldehyde, 36% w./v 0.5

The polymerisation, precipitation and drying of the polymer were carriedout in precisely the same manner as described in Example 7. The polymerhad a second order transition point, Tm, of 100 C. It was insoluble inbenzene or in dimethyl formaldehyde, but was highly swollen to give analmost clear gel.

A sample of the polymer, after being baked for 72 hours at 100, was moreresistant to benzene and dimethylformamide; the second order transitionpoint, after baking, was substantially unchanged at 101.8" 0.

Alternatively, according to a modified form of this invention, preformedcompounds obtained by the reaction of formaldehyde with p-vinylbenzamidesuch as N-methylol-p-vinylbenzamide may be polymerised alone orcopolymerised with styrene or other comonomers and the resulting polymeror copolymer subsequently cross linked by heating, as shown in Example12.

The above mixture was warmed to 80 C. for 10 minutes and allowed tostand 18 hours at 50 C. Excess formaldehyde and water were then Thepolymer removed by warming under reduced pressure. The product was awhite micro-crystalline powder,.M. Pt. 128-9 C'., N content 7.4%,(Kjeldahl), probably mainly N-methylol p-vinylbenzamide.

30 parts by weightof 2 sodium stearate solution containing-0.1% w./v. ofammonium persulphate and parts by weight of styrene were then added andthe containing vessel was sealed. An emulsion was made by vigorousagitation and polymerisation was carried out by heating for 24 hourswith continuous agitation in a thermostat maintained'at 50 C. Aftersteam stripping to remove residual monomenthe polymer was obtained byprecipitating and drying in the usual manner.

By way of comparison, a sample of polystyrene was prepared in aprecisely analogous manner, the only differences being that theN-methylol vinylbenzamide was omitted and the time of heating increasedto 42 hours to ensure complete polymerisation. A sample of this polymerwas soaked for 27 hours in 36% w./v. formaldehyde solution made alkalineby the addition of a small amount of dilute sodium carbonate solution.

- The polymer was then washed in distilled water and dried in air. Itwas found to have a second order transition point Tm of 93.8.

Samples of (a) the copolymer of styrene and N-methylolvinylbenzamide and(b) formaldehyde-treated styrene polymer were then baked for 24 hours inan air oven at 100 C.

The untreated polystyrene sample was completely soluble in benzene togive a clear viscous solution, the sample (b) which had been treatedwith formaldehyde and subsequently baked, showed no detectabledifference in appearance or benzene solubility and, as would beexpected, it appeared to be substantially unchanged by this treatment,having a Tm of 92.7.

The copolymer (a), on the other hand, both before and after heattreatment was insoluble in benzene, but was swollen to give an opaquegel. After heat treatment, the value of Tm was 99 C.

Example 13 This example illustrates the method of crosslinking astyrene-p-vinylbenzamide copolymer by hot milling with a compoundcapable of giving free formaldehyde, namely para-formaldehyde. A mixtureof 20 parts by weight styrene, 0.2 part by weight p-vinylbenzamide and0.02 part by weight benzoyl peroxide was heated for 48 hours at 80 C. togive a transparent, homogeneous copolymer. This was readily pressed atC. to give a clear, colourless sheet. Samples of the pressed polymerwere readily soluble in benzene to give a clear solution.

5 parts by weight of the copolymer were mixed with 0.5 part ofparaformaldehyde and milled on steam-heated rolls at C. for 10 minutes.The sample, after milling, was insoluble in benzene and dimethylformamide.

In addition to formaldehyde and its polymers, other reactivemethylol-group-containing materials may be employed as cross-linkingagents in substantially the same way, amongst which may be mentioneddimethylolurea, hexamethylolmelamine and condensation products offormaldehyde and phenols which liberate formaldehyde on heating; ethersderived from such compounds, such as hexamethoxymethylmelamine, may alsobe employed.

While only styrene has been exemplified as comonomer, other materialscopolymerisable with styrene may be used under substantially the sameconditions as they arewith the lajtter mun-z omer, including dienehydrocarbons such as butadiene, acrylic esters such as ethylacryl-ate,methacrylic esters such as methylmethacrylate,

maleic anhydride, drying oils such as linseed and 5 tung oils and theirfatty acids, polymerisable unsaturated alkyd resins such as polyethyleneglycol maleate, and oil-modified alkyd resinsi.

We claim:

The substance N-methyloi p' vinyl benzamide. 10

JOHNVNOEL MILNE. DONALD FAULKNER. CHARLES EDWARD HOLLIS.

8 References Cited'in the file 01.- this patent. UNITED STATES PATENTSNumber Name Date 2,500,025 Dickey et a1 Mar. 7, 1950 2,520,917 Dickey eta1; Sept. 5, 1950 OTHER REFERENCES Matsui: J Soc. Chem. Ind. Japan, vol.46 (1943), Supplemental Binding 1-25, p. 126.

Snyderet a1.: fJ, Am. Chem. $00.," v01. 71 (Mar.1949),pp.1'0'57and 1058.r I

Chem. Abstri, v01. 44" (1950), pp. 9187 and 9188. v

